LTE-Advanced (Rel-10/11) March 2013 Bong Youl (Brian) Cho, 조 봉 열
[email protected]
Contents • LTE-Advanced Overview • LTE-Advanced Technologies – – – – – –
eICIC for HetNet
Relay MIMO Enhancement CoMP Carrier Aggregation SON
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LTE-Advanced Overview
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3GPP 표준 Release 일정 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Release 99 W-CDMA Release 4 1.28Mcps TDD
Release 5 HSDPA Release 6 HSUPA, MBMS Release 7 HSPA+ (MIMO, HOM etc.)
ITU-R M.1457 IMT-2000 Recommendation
ITU-R M.2012
Release 8 LTE Release 9 Minor LTE enhancements Release 10 LTE-Advanced
IMT-Advanced Recommendation
Release 11 Note: • 3GPP 표준에는 GSM, WCDMA/HSPA, LTE 기술이 모두 포함되어 있으며, 3가지 기술 모두가 지속적으로 진화함 • LTE-Advanced는 LTE와는 별도의 기술이 아니라 LTE의 진화의 한 경로 혹은 단계임 TTA LTE Standards/Technology Training 4 © Nokia Siemens Networks
Release 12
3GPP Releases
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Radio Technology Evolution 2020+ 2015+
2010+
LTE Advanced Evolution 2013+ Rel-12 and Rel-13 LTE Advanced Small cells for Rel-10 and Rel-11 capacity boost
LTE Rel-8 and Rel-9
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Beyond 4G
Squeeze macro cells
Local area radio
LTE 및 LTE-A 단말 카테고리 (클래스) LTE-Advanced 단말 카테고리 (Rel-10)
현재 및 가까운 미래의 LTE 단말 (Rel-8)
Class 1 Peakrate DL/UL
Class 2
Class 3
Class 4
Class 5
Class 6
10/5 Mbps 50/25 Mbps 100/50 Mbps 150/50 Mbps 300/75 Mbps 300/50 Mbps
Class 7
Class 8
300/100 Mbps 3000/1500Mbps
RF Bandwidth
20 MHz
20 MHz
20 MHz
20 MHz
20 MHz
40 MHz
40 MHz
100 MHz
Modulation DL
64 QAM
64 QAM
64 QAM
64 QAM
64 QAM
64 QAM
64 QAM
64 QAM
Modulation UL
16 QAM
16 QAM
16 QAM
16 QAM
64 QAM
16 QAM
16 QAM
64 QAM
MIMO DL
optional
2x2
2x2
2x2
4x4
2 x 2 or 4 x4
2 x 2 or 4 x 4
8x8
MIMO UL
no
no
no
no
no
no
2x2
4x4
• • • • •
현재 상용 LTE 단말은 Cat-3 or 4이지만 10MHz BW를 사용하므로 최대 DL 75Mbps, UL 25Mbps 임 Cat-5 단말은 DL 300Mbps를 위하여 20MHz & 4x4 MIMO를 사용함. Cat-6 단말은 DL 300Mbps를 위하여 40MHz & 2x2 MIMO를 사용함. CA 단말기 Cat-7 단말은 UL에 2x2 MIMO가 적용되어 UL 100Mbps 임 Cat-8 단말은 LTE-Advanced의 PDR을 높이는 모든 기술이 적용된 것임 • 100MHz BW & 8x8 MIMO => DL 3Gbps • 100MHz BW & 4x4 MIMO => UL 1.5Gbps
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시스템 성능 향상 및 요구사항 (목표) •
주파수 효율 (Spectral Efficiency, SE) • •
단위 주파수 당 보낼 수 있는 데이터의 양: bit/sec/Hz 주요 시스템 성능 지표로 사용
• •
Rel8 LTE 의 성능 요구사항 (목표)는 Rel6 HSPA 대비 3배 정도의 SE 향상이었음 Rel10 LTE-Advanced의 성능 요구사항 (목표)는 Rel8 LTE 대비 약 1.4~1.6배 정도의 SE 향상임.
•
셀 전체 성능과 함께 셀 가장자리 성능도 중요
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시스템 성능 향상을 할 수 있는 방안? •
셀룰러망 (cellular network)에서의 주파수 재사용 (frequency reuse)의 극대화? • • •
•
셀룰러 망의 문제점 극복? • • •
•
인접 셀들 사이에서 동일한 주파수를 사용하면서 서로 다른 데이터를 전송하면 이들 사이에는 필연적으로 간섭이 존재 셀 가장자리의 data rate 저하 이를 극복하는 방안 중 하나가 협력통신 (Cooperative Multi-Point transmission and reception, CoMP)
안테나 사용의 극대화? •
•
동일한 주파수를 최대한 자주 재사용하여 전체 망의 용량을 증대 기존의 AMPS의 주파수 재사용율 7에 비해 CDMA부터 재사용율 1을 사용 (즉, 인접 셀들이 모두 같은 주파수를 사용) 셀의 크기가 작아지고 셀의 개수가 많아지면 전체 망의 용량이 증대될 수 있음 Small cell: Macro > Micro > Pico > Femto HetNet (Heterogeneous Network)
Higher order MIMO: 2x2 4x4 8x8
더 많은 주파수의 사용? • • •
용량 = 주파수 효율 x 주파수 사용량 주파수 효율을 올리기 힘들면, 주파수를 많이 사용하자 “모바일 광개토 플랜” 이왕 여러 주파수를 사용하는 바에는 이를 하나처럼 합치자 Carrier Aggregation
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LTE-Advanced: Five major technologies Heterogeneous Networks
높은 SINR 환경에서의 추가적인 peak data rate 증대 [Rel-10]
Small cell의 활용 Micro/Pico/Femto [Rel-10]
Relaying
인접 셀들 사이의 상호 조정 및 협력을 통하여 셀 간 간섭을 줄임으로써, 셀 가장자리 성능 향상을 꾀함 [Rel-11]
BW를 합침으로써 사용자당 peak data rate 증대 [Rel-10]
8x
MIMO MIMO
Coordinated Multipoint
Carrier Aggregation up to 100 MHz 100 MHz
Carrier1 Carrier2 Carrier3
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4x
…
Carrier5
Repeater의 진화? Repeater와 기지국의 중간 정도 되는 장비 [Rel-10]
HetNet: Interference Management
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Network Densification • Homogeneous network • Heterogeneous network
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HetNet
– problems in non-homogeneous deployment
• Consist of deployments where low power nodes are placed throughout a macro-cell layout
• The interference characteristics in a heterogeneous deployment can be significantly different than in a homogeneous deployment
• Mainly, two different heterogeneous scenarios are under consideration – Macro-Femto (CSG: Closed Subscriber Group) case – Macro-Pico case
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Motivation for new ICIC techniques • The frequency domain ICIC is not sufficient. – Because DL control channels (PCFICH/PHICH/PDCCH) are spread over the entire system bandwidth.
– With a cell-specific interleaving structure
• ICIC in another resource domain becomes necessary TTA LTE Standards/Technology Training 14 © Nokia Siemens Networks
Range Extension (of picocell) • The current “cell selection” algorithm is DL oriented • So, it may not be the optimum for UL perspective. • Further more, too high DL power of macro cell is too costly in cellular network Range extension of picocell but, this can lead to significant interference issue in extended range
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Why “ALMOST” blank subframe? • Because some channels/signals should be transmitted for the legacy UE operation. – CRS (If ABS coincides with MBSFN subframe not carrying any signal in data region, CRS is not present in data region )
– PSS, SSS, and PBCH – PRS and CSI-RS – SIB1/Paging with associated PDCCH
• No other signal is transmitted • Some interference still exists. – To be studied in the next release.
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Coordination between two cell layers
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TDM eICIC Principle
- combined macro+pico+HeNB case Pico-nodes can schedule UEs with larger RE, if not interfered from nonallowed CSG HeNB(s)
Almost blank, or MBSFN sub-frame Sub-frame with normal transmission
Macro-layer Pico-UEs with larger RE, close to CSG HeNB(s) are schedulable
Pico-layer
HeNB-layer
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Macro-eNBs and Pico-eNBs can schedule also users that are close to non-allowed CSG HeNB(s), but not pico-UEs with larger RE.
Baseline Assumptions for Network Configuration of Muting Patterns • Macro + HeNB scenario:
Centralized concept
– Muting patterns are assumed to be statically configured from OAM – Both macro and HeNB needs to know the muting pattern: HeNB will apply the muting pattern (i.e. will mute some of its subframes) Macro-eNB needs to know so it only schedule its users close to non-allowed CSG HeNBs during muted subframes + can configured Rel-10 UEs with appropriate measurement restrictions.
• Macro + pico scenario:
Distributed concept
– Muting patterns are assumed to be dynamically configured, assisted by new X2 signalling introduced in Rel-10.
– Both macro and pico needs to know the muting pattern: Macro-eNB will apply the muting pattern (i.e. will mute some of its subframes) Pico-eNB needs to know so it only schedule its users with large range extension
during muted subframes + can configured Rel-10 UE measurement restrictions for those UEs.
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TS36.423 X2AP: Load Information 9.1.2.1
LOAD INFORMATION
This message is sent by an eNB to neighbouring eNBs to transfer load and interference co-ordination information. Direction: eNB1 eNB2. IE/Group Name Message Type Cell Information >Cell Information Item
Presence
Range
IE type and reference
Semantics description
M M 1 .. Id of the source cell
YES YES EACH
Assigned Criticality ignore ignore ignore
–
–
–
–
–
–
–
–
>>Cell ID
M
>>UL Interference Overload Indication >>UL High Interference Information >>>Target Cell ID
O
>>>UL High Interference Indication >>Relative Power (RNTP) >>ABS Information >>Invoke Indication
M
–
–
O O O
– YES YES
– ignore ignore
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ECGI
Criticality
0 .. M
ECGI
9.2.54 9.2.55
Id of the cell for which the HII is meant
TS36.423 ABS Information IE
IE/Group Name CHOICE ABS Information >FDD >>ABS Pattern Info
>>Number Of Cell-specific Antenna Ports >>Measurement Subset
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Presence M M
M M
Range
IE type and reference
Semantics description
– – BIT STRING (SIZ E(40))
– – Each position in the bitmap represents a DL su bframe, for which value "1" indicates ‘ABS’ and value "0" indicates ’non ABS’. The first position of the ABS pattern correspon ds to subframe 0 in a radio frame where SFN = 0. The ABS pattern is continuously repeated in all radio frames. The maximum number of subframes is 40. P (number of antenna ports for cell-specific ref erence signals) defined in TS 36.211 [10] Indicates a subset of the ABS Pattern Info abo ve, and is used to configure specific measurem ents towards the UE.
ENUMERATED ( 1, 2, 4, …) BIT STRING (SIZ E(40))
New X2 eICIC Related Signalling • ABS information in IE
eNB
eNB
– This IE provides information about which sub
frames the sending eNB is configuring as almost blank subframes and which subset of almost blank subframes are recommended for configuring measurements towards the UE.
X2-AP: LOAD INFORMATION
– Macro can signal ABS muting pattern to the pico nodes in ABS information IE. – A neighbouring macro-cell receiving this information may aim at using similar muting pattern (but it is optional if macro-eNB follows such recommendation).
• Invoke information IE – This IE provides an indication that the sending eNB would like to receive ABS information.
– Can be used by pico nodes to suggest macro-eNB to start scheduling ABS, i.e. that the pico serves UEs suffering high interference.
• Both the ABS information IE and/or Invoke IE is part of the LOAD
INFORMATION message. Therefore, both of them can be exchanged between any two eNBs connected with X2, also between macros.
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New X2 eICIC Related Signalling (cont’) • Macro-eNB can send a resource request to the pico-eNB.
• Pico-eNB response with ”ABS status”
eNB1
eNB2 RESOURCE STATUS REQUEST
RESOURCE STATUS RESPONSE
9.2.58 ABS Status The ABS Status IE is used to aid the eNB designating ABS to evaluate the need for modification of the ABS pattern. DL ABS status
>> Usable ABS Pattern Info
M
INTEGER (0..100)
Percentage of resource blocks of ABS allocated for UEs protected by ABS from inter-cell interference. This includes resource blocks of ABS unusable due to other reasons. The denominator of the percentage calculation is indicated in the Usable ABS Information.
M
BIT STRING (SIZE(40))
Each position in the bitmap represents a subframe, for which value "1" indicates ‘ABS that has been designated as protected from inter-cell interference’ and value "0" indicates ‘ABS that is not usable as protected ABS from inter-cell interference’. The pattern represented by the bitmap is a subset of, or the same as, the corresponding ABS Pattern Info IE conveyed in the LOAD INDICATION message.
• The ”ABS status” is basically a load measure of how much the pico-eNB uses the subframes where the macro-eNB is muted.
• It is intended that only ABS allocated to UEs that would not cope otherwise are reported • This information can be used by the macro-eNB to get an idea of the consequences of
increasing/decreasing the number of muted subframes. It can be combined with information about overall load in the pico.
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CSI Measurement for eICIC • Clearly, the interference experienced by pico-cell terminals may vary significantly between protected and non-protected subframes.
• CSI measurements carried out jointly on both the protected and non-protected subframes will thus not accurately reflect the interference of either type of subframes.
• Thus, as part of the enhanced support for heterogeneous network deployments, it is possible to configure a terminal with different CSI-measurement subsets , confining the terminal CSI measurements to subsets of the full set of subframes with terminals reporting CSI for each subset separately.
• The corresponding CSI reports should then preferably reflect the interference level in protected and nonprotected subframes respectively.
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UE Operation for eICIC: Example
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FeICIC in Rel-11 • eICIC is introduced in LTE Rel-10 and further enhanced in Rel-11 – eICIC = enhanced Inter Cell Interference Coordination – FeICIC = Further enhanced Inter Cell Interference Coordination
• eICIC consists of three design principles – Time domain interference management (Rel-10) Severe interference limits the association of terminals to low power cells
– Cell range expansion (Rel-10/11) Time domain resource partitioning enables load balancing between high and low power cells Resource partitioning needs to adapt to traffic load
– Interference cancellation receiver in the terminal (Rel-11/12) Ensures that weak cells can be detected Inter cell interference cancellation for control signals (pilots, synchronization signals)
Ensures that remaining interference is removed Inter cell interference cancellation for control and data channels (PDCCH/PDSCH
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* source: Qualcomm
FeICIC Performance
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* source: Qualcomm
FeICIC Performance – cont’d
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* source: Qualcomm
Relay
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Relay • Relay – Repeater 보다는 똑똑하면서 기지국보다는 간단하고 저렴한 솔루션? – HeNB (femto cell) 출현 및 Macro 기지국의 간단 저렴화
• Rel-10 relay deployment scenario – Decode-and-forward relay – Self-backhauling was taken as the basis for the LTE relaying
– Stationary relay – Single hop relay
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In-band Relay • Interference b/w access link and backhaul link
• Using MBSFN subframe for relay operation Multiplexing b/w access and backhaul links
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MIMO Enhancement
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MIMO (Multiple Input Multiple Output) •
이는 “채널” 관점에서의 용어임 – 채널 관점에서 Multiple Input 복수 개 (NT)의 송신 안테나 – 채널 관점에서 Multiple Output 복수 개 (NR)의 수신 안테나 • MxN으로 표시하기도 함 – 2x2 MIMO: 송신 안테나 2개, 수신 안테나 2개 – 4x4 MIMO: 송신 안테나 4개, 수신 안테나 4개
•
SIMO (Single Input Multiple Output) – NR 개의 수신 안테나 = 수신안테나 다이버시티 • MISO (Multiple Input Single Output) – NT 개의 송신 안테나 = 송신안테나 다이버시티
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무선 채널 (H)
Higher Order MIMO를 통한 성능 개선 • MxN MIMO 사용시, 서로 다른 안테나로 최대 min(M, N)개의 서로 다른 심볼을 동시에 보낼 수 있음 – – –
2x2 MIMO 사용 시, data rate이 MIMO 미사용 대비 최대 2배 빨라질 수 있음 4x2 MIMO 사용 시, data rate이 MIMO 미사용 대비 최대 2배 빨라질 수 있음 4x4 MIMO 사용 시, data rate이 MIMO 미사용 대비 최대 4배 빨라질 수 있음
• Rel-8 표준 상으로는 DL 4x4까지 지원되고, UL는 SU-MIMO이 지원되지 않음 실제 제품은 4Rx를 지원하는 단말이 없어, DL 2x2가 최대임.
• Rel-10에서는 DL 8x8 및 UL 4x4를 표준적으로 정의하여,
이론적으로는 Rel-8 대비 DL PDR (peak data rate) 2배 증가 및 UL PDR 4배 증가를 꾀함 – – –
단말기에 수신 안테나가 8개가 있어야 함 단말기에 송신 안테나 4개 및 power amplifier 4개가 있어야 함 Higher order MIMO가 동작하려면 SINR (Signal to Interference and Noise Ratio)가 매우 높아야 함.
Max. 8 streams
Higher-order MIMO up to 8 streams TTA LTE Standards/Technology Training 34 © Nokia Siemens Networks
Max. 4 streams
SU-MIMO up to 4 streams
SVD MIMO as a closed-loop MIMO • In CL-SU-MIMO, SVD-MIMO is the optimum
?
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MIMO Channel Decomposition ~ w 1
1
y
x ~x
V
VH n
U
UH
~ w nmin
min
Channel
Pre-processing
Post-processing
With number of transmitting antenna=nt and receiving antenna=nr,
y Hx w x C nt , y C nr , w ~ Ν (0, N 0 I nr ) TTA LTE Standards/Technology Training 36 © Nokia Siemens Networks
~ y
Channel Diagonalization H ~ yU y
U (Hx w ) H
U H (UDV H x w ) U H (UDV H V~ x w) D~ x UHw
~ ~ y D~ xw
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Spatial Diversity • Benefits of Spatial Diversity – – – –
Array gain Diversity gain and decreased error rate Increased data rate Increased coverage or reduced transmit power
• Receive Diversity – Selection combining, Equal gain combining, and Maximal radio combining (MRC)
• Transmit Diversity – Open-loop transmit diversity: e.g., Alamouti coding – Closed-loop transmit diversity: e.g., Linear precoding y = G(HFx + n) where x is the transmited symbol vector, y is the received symbol vector with M x 1, G is the post-coder matrix with M x Nr, H is the channel matrix with Nr x Nt, F is the precoder matrix with Nt x M For the diversity precoding, M = 1, and the SNR maximizing precoder F and postcoder G are the right- and left- singular vectors of H corresponding to its singular value, max. TTA LTE Standards/Technology Training 38 © Nokia Siemens Networks
Beamforming • DOA (Direction-Of-Arrival)-based Beamforming – Physically directed – Incoming signals to a receiver may consist of desired energy and interference energy. – From the acquired DOAs, a beamformer extracts a weighting vector for the antenna elements and uses it to transmit or receive the desired signal of a specific user while suppressing the undesired interference signals. – Often called null-steering beamformer – Viable only in LOS environments or in environments with limited local scattering around the transmitter
• Eigen Beamforming – Mathematically directed – Eigen beamforming exploits CSI of each antenna element to find array weights that satisfy a desired criterion, such as SNR maximization or MSE minimization. – Eigen beamforming is conceptually nearly identical to the linear diversity precoding,
the only difference being that the eigen beamforming takes interfering signals into account. – More viable in realistic wireless broadband environments, which are expected to have significant local scattering TTA LTE Standards/Technology Training 39 © Nokia Siemens Networks
3GPP Release 8 LTE DL transmission modes Two approaches to multi-antenna transmission MIMO CQI PMI Rank
Beamforming CQI SRS
CRS
DRS
MCS PMI Rank
MCS
PDSCH Channel estimation based on common reference signal (CRS)
PDSCH Channel estimation based on dedicated reference signal (DRS)
Closed loop, codebook precoding (#4)
Non-codebook precoding (#7)
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3GPP Release 9 LTE DL transmission modes Enhanced beamforming: dual-layer beamforming (#8) CQI PMI Rank SRS DRS
MCS Rank
PDSCH Channel estimation based on DRS TTA LTE Standards/Technology Training 41 © Nokia Siemens Networks
Multi-Antenna Technology Summary • Diversity – Same data on all the pipes Increased coverage and link quality – But, the all pipes can be combined to make a kind-of beamforming
• MIMO – Different data streams on different pipes (mode 4) Increased spectral efficiency (increased overall throughput) Power is split among the data streams
• Beamforming – Data stream on only the strongest pipe (mode 7) Use all the power on the strongest pipe (i.e., the most efficient pipe) Increased coverage and signal SNR – Not any more focusing on the strongest pipe in transmission mode 8 in R9 – Further enhanced in transmission mode 9 in R10
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Precoding • Codebook-based • Non-codebook-based
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DL MIMO Trend
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New RS Types in Downlink for LTE-A
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RS configuration in LTE-A network • Support of Rel-8 Common RS – LTE-A eNB should always support LTE UE as well – Rel-8 CRS is also used for LTE-A UEs to detect PCFICH, PHICH, PDCCH, PBCH and PDSCH (TxD only)
• DM-RS + CSI-RS based approach – Main motivation is to reduce RS overhead – DM-RS for demodulation of PDSCH only (except TxD)
UE specific Transmitted only in scheduled RBs and the corresponding layers RSs on different layers are mutually orthogonal RS and data are subject to the same precoding operation
– CSI-RS for measurement Transmitted by puncturing PDSCH RE in a duty cycle Idea is that CSI-RS overhead can be made very small (e.g. less than 1% for 8Tx antenna support)
– Independent antenna configuration Although LTE-A antenna port is larger than 4Tx, Rel-8 antenna port can be defined less than 4Tx Any combination is possible b/w the number of LTE-A CSI-RS ports and the number of CRS ports TTA LTE Standards/Technology Training 46 © Nokia Siemens Networks
PDSCH Transmission Modes TM
Details
RS for demodulation
1
Single-antenna transmission
CRS (R0)
2
Transmit diversity
CRS (R0…R3)
3
Open-loop codebook-based precoding in the case of more CRS (R0…R3) than one layer, transmit diversity in the case of rank-one transmission
4
Closed-loop codebook-based precoding
CRS (R0…R3)
5
Multi-user-MIMO version of transmission mode 4
CRS (R0…R3)
6
Special case of closed-loop codebook-based precoding limited to single-layer transmission
CRS (R0…R3)
7
Rel-8 non-codebook-based precoding supporting only single-layer transmission
UE-specific RS (R5)
8
Rel-9 non-codebook-based precoding supporting up to two layers
UE-specific RS (R7,R8)
9
Rel-10 non-codebook-based precoding supporting up to eight layers
UE-specific RS (R7…R14)
10
Rel-11 non-codebook-based precoding supporting up to eight layers (suitable for CoMP)
UE-specific RS (R7…R14)
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CoMP
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CoMP Operations – CS/CB, JT
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DL CoMP Schemes
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DL CoMP Schemes
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UL CoMP Schemes
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CoMP Sets • CoMP cooperating set – Set of (geographically separated) points directly or indirectly participating in PDSCH transmission to UE.
• CoMP transmission point(s) – Point or set of points actively transmitting PDSCH to UE – A subset of the CoMP cooperating set
• CoMP measurement set – Set of points about which channel state/statistical information related to their link to the UE is measured and/or reported
TTA LTE Standards/Technology Training 53 © Nokia Siemens Networks
CoMP Scenarios in 3GPP TR 36.819 • Scenario 1: Homogeneous network with intra-site CoMP • Scenario 2: Homogeneous network with high Tx power RRHs • Scenario 3: Heterogeneous network with low power RRHs within the macrocell coverage where the transmission/reception points created by the RRHs have different cell IDs as the macro cell
• Scenario 4: Heterogeneous network with low power RRHs within the macrocell coverage where the transmission/reception points created by the RRHs have the same cell IDs as the macro cell
eNB
High Tx power RRH
Coordination area Optical fiber
Assume high Tx power RRH Scenario 1 - Homogeneous network with intrasite CoMP
TTA LTE Standards/Technology Training 54 © Nokia Siemens Networks
Scenario - Homogeneous network with high Tx as same2 as eNB power RRHs
eNB Low Tx power RRH (Omni-antenna) Optical fiber Scenario 3/4 - Network with low power RRHs within the macrocell coverage
R8 CRS for TM1…6: resource mapping One antenna port
R0
R0
R0
R0
R0
R0
R0
R0
l0
l6 l0
l6
Resource element (k,l)
Two antenna ports
R0
R0
R0
R0
R1
R0
R0
R0
Four antenna ports
R0
R0
l0
R0
odd-numbered slots
port 0 TTA LTE Standards/TechnologyAntenna Training 55 © Nokia Siemens Networks
l0
R2
R1
R3
R2
R1 l6 l0
even-numbered slots
R3
R2 l6
odd-numbered slots
Antenna port 1
R3
R2
R1
R1 l6
l6
R1
R1
R0 l6 l0
even-numbered slots
R1
R1
R0
Reference symbols on this antenna port
l6 l0
R1
R0
R0
l0
l6
Not used for transmission on this antenna port
R1
R1
l6 l0
R0
R1
R1
R0
l0
R1
R1
l0
R3 l6 l0
even-numbered slots
l6
odd-numbered slots
Antenna port 2
l0
l6 l0
even-numbered slots
l6
odd-numbered slots
Antenna port 3
R8 UE-specific RS for TM7: resource mapping • UE-specific RS (antenna port 5) – 12 symbols per RB pair • DL CQI estimation is always based on cell-specific RS (common RS)
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R9 UE-specific RS for TM8: resource mapping
TTA LTE Standards/Technology Training 57 © Nokia Siemens Networks
R10 UE-specific RS for TM9/10: resource mapping
TTA LTE Standards/Technology Training 58 © Nokia Siemens Networks
R8 CRS for TM1…6: sequence • The reference-signal sequence is defined by rl ,ns (m)
1 2
1 2 c(2m) j
1 2
1 2 c(2m 1),
max,DL m 0,1,...,2 N RB 1
where the pseudo-random sequence generator shall be initialised with
cell cell cinit 210 7 ns 1 l 1 2 N ID 1 2 N ID N CP
at the start of each OFDM symbol Cell specific
TTA LTE Standards/Technology Training 59 © Nokia Siemens Networks
R8 UE-specific RS for TM7: sequence • The reference-signal sequence is defined by rns (m)
1 2
1 2 c(2m) j
1 2
1 2 c(2m 1),
PDSCH m 0,1,...,12 N RB 1
where the pseudo-random sequence generator shall be initialised with
cell cinit ns 2 1 2 N ID 1 216 nRNTI
at the start of each subframe UE specific within a cell
TTA LTE Standards/Technology Training 60 © Nokia Siemens Networks
R9 UE-specific RS for TM8: sequence • The reference-signal sequence is defined by r (m)
1 2
1 2 c(2m) j
1 2
1 2 c(2m 1),
max,DL m 0,1,...,12 N RB 1
where the pseudo-random sequence generator shall be initialised with
cell cinit n s / 2 1 2 N ID 1 216 nSCID
at the start of each subframe UE specific within a cell
TTA LTE Standards/Technology Training 61 © Nokia Siemens Networks
R10 UE-specific RS for TM9: sequence • The reference-signal sequence is defined by r (m)
1 1 2 c(2m) j 1 1 2 c(2m 1), 2 2
max,DL m 0,1,...,12 N RB 1
where the pseudo-random sequence generator shall be initialised with
cell cinit n s / 2 1 2 N ID 1 216 nSCID
at the start of each subframe UE specific within a cell
TTA LTE Standards/Technology Training 62 © Nokia Siemens Networks
R11 UE-specific RS for TM10: sequence • The reference-signal sequence is defined by r (m)
1 1 2 c(2m) j 1 1 2 c(2m 1), 2 2
max,DL m 0,1,...,12 N RB 1
where the pseudo-random sequence generator shall be initialised with
( nSCID ) cinit ns / 2 1 2nID 1 216 nSCID
at the start of each subframe UE specific within a virtual cell (i ) cell - nID nID (i ) DMRS,i nID - nID
TTA LTE Standards/Technology Training 63 © Nokia Siemens Networks
DMRS,i is provided by higher layers if no value for nID otherwise
R10 CSI-RS for TM9/10: resource mapping • CSI-RS is transmitted by puncturing data RE on both LTE Rel-8/9 and LTE-Adv PDSCH – CSI-RS is regarded as data RE to LTE UE – Some performance impacts on the legacy UEs are inevitable Loss of information due to puncturing, Interference from CSI-RS R15 R15
R16 R16
R18 R18
R17 R17
l0
l6 l0
l6
l0
R19 R19
l6 l0
l6
l0
l6 l0
l6
l0
l6 l0
even-numbered slots
l6
R20 R20
R21 R21
l0
l6 l0
l6
odd-numbered slots
TTA LTE Standards/Technology Training 64 © Nokia Siemens Networks
l0
l6 l0
even-numbered slots
l6
odd-numbered slots
l0
R22 R22
l6 l0
even-numbered slots
l6
odd-numbered slots
l0
l6 l0
even-numbered slots
l6
odd-numbered slots
R10 CSI-RS for TM9: sequence • The reference-signal sequence is defined by rl ,ns (m)
1 2
1 2 c(2m) j
1 2
1 2 c(2m 1),
max,DL m 0,1,...,N RB 1
where the pseudo-random sequence generator shall be initialised with
cell cell cinit 210 7 ns 1 l 1 2 N ID 1 2 N ID N CP
at the start of each OFDM symbol cell specific
TTA LTE Standards/Technology Training 65 © Nokia Siemens Networks
R11 CSI-RS for TM10: sequence • The reference-signal sequence is defined by rl ,ns (m)
1 2
1 2 c(2m) j
1 2
1 2 c(2m 1),
max,DL m 0,1,...,N RB 1
where the pseudo-random sequence generator shall be initialised with cinit 210 7 ns 1 l 1 2 nID 1 2 nID N CP
at the start of each OFDM symbol virtual cell specific
• A UE in transmission mode 10 can be configured with one or more CSI processes per serving cell by higher layers.
Therefore UE can send CSI of each TP in independently. (support to do CS/CB, DPS, JT) TTA LTE Standards/Technology Training 66 © Nokia Siemens Networks
Cell agnostic operation • UE is camping to one serving cell as in R8 (following process is with serving cell) •Synchronize with PSS/SSS/CRS, identify cell id, read SI
•UE transmit PUSCH targeting to a virtual cell, network can decide which cell to receive it. •UE receive PDSCH without know which cell it comes from TTA LTE Standards/Technology Training 67 © Nokia Siemens Networks
CSI-RS
ePDCCH
UE doesn’t know which cell this channel is from/to
PDSCH
•eNB schedule PDSCH/PUSCH through ePDCCH
PUSCH
•UE measure the CSI-RS from eNB and feedback CSI.
RI/PMI/ CQI
UE
•eNB can configure Resource management set for UE to measure CSI-RS RSRP to help determining CoMP set. •eNB can configure CoMP measurement set including multiple CSI-RS resource to one UE.
RRM/RLM
• Cell agnostic operation can work after RRC setup is done.
PDCCH
RACH
•RRC configuration message is carried by PDSCH and PDCCH based on cell specific CRS
PSS/SSS
•RRM/RLM measurement is performed on cell specific CRS, Handover is also cell specific.
CRS/SI
•RACH and PDCCH are cell specific
From/to serving cell
Beam-switching vs Handover • Beam Switching – Moving between Beams in the Same Base Station (Low-Layer Procedure)
• Handover – Moving between Beams of different Base Stations (HighLayer Procedure)
TTA LTE Standards/Technology Training 68 © Nokia Siemens Networks
* source: ERTI
LTE Downlink spectral efficiency gains (Full buffer, macro network, up to 4 BS antennas)
100,00% 80,00%
• (DL) Dynamic Cell Selection
30% gain over 4x2 reference case
120,00%
•
3GPP 4x2 reference case Viable 4 BS TX intrasite evolution target
•
60,00% 40,00%
Best choice for 2x2 configuration
20,00% 0,00% -20,00%
Intra JP- 9-cell UE- Intra DCS CoMP centric JPCoMP Intra-site
Inter-site
R8 SU R10 SU/MU Intra JPMIMO MIMO CoMP
Intra-site Single-cell Single-cell Intra-site
NonNonquantized quantized feedback feedback
Rel-11 CoMP 2 x 2 Configuration
TTA LTE Standards/Technology Training 69 © Nokia Siemens Networks
Inter JP- Intra CS/CB Inter CS/CB Intra JP- 9-cell UECoMP CoMP CoMP CoMP centric JPCoMP Inter-site
Codebook Codebook
Intra-site
Inter-site
SRS
SRS
Rel-11 CoMP 4 x 2 Configuration
Intra-site
Inter-site
NonNonquantized quantized feedback feedback Non-realistic CoMP But just a reference
is the best choice in the 2 TX BS antenna case. Decisive gains in DL are obtained when increasing to 4 TX or even 8 TX BS antennas. DL JT CoMP 4x2 techniques provide some additional gain compared to R10 MU 4x2 MIMO in case of UEcentric inter-site JT and non-quantized CSI feedback.
Reference: R8 2x2 SU MIMO; Sector SE (cell throughput): 2.1 Bps/Hz/Cell Cell Edge SE (5%-tile CDF): 0.7 Bps/Hz/Cell Environment: MMSE UE receiver, FDD, Macro Case 1, Full Buffer, Uncorrelated, cross-polar BS antennas *NSN results are included in 3GPP TR36.819
LTE Uplink spectral efficiency gains
(Full buffer, macro network, up to 4 BS antennas) CoMP gains vary with assumed receiver type.
• • •
•
Intra-site evolution
Achieving decisive UL performance gains requires 4RX antennas per sector. UL JR-CoMP gives attractive Cell Edge and Sector SE gains also as part of intra-site evolution. Gains from inter-site JR-CoMP are increased when power settings are changed to trade-off cell edge SE gains for sector SE gains. UL JR-CoMP does not require standard support, but standard support will enhance UL JR-CoMP performance. • ~25% sector SE gain and ~50% cell
•
CoMP 2 RX antennas per sector TTA LTE Standards/Technology Training 70 © Nokia Siemens Networks
CoMP 4 RX antennas per sector
edge SE gain over 2 Rx IRC can be achieved with intra-site 2 Rx JR CoMP ~20% sector SE gain and ~30% cell edge SE gain over 4Rx IRC with MUMIMO can be achieved with intra-site 4Rx JR CoMP
Reference: Sector SE (cell throughput): 0.85 Bps/Hz/Cell Cell Edge SE (5%-tile CDF): 0.04 Bps/Hz/Cell @ MRC, Single cell, 2 Rx Environment: FDD, Macro Case 1, Full Buffer, Uncorrelated, crosspolar BS antennas Power settings (also in reference) emphasize cell edge SE Receiver types: Interference cancellation w/ IRC IRC (single cell) or reduced complexity IRC (CoMP) * NSN result are included in 3GPP TR36.819
Carrier Aggregation
TTA LTE Standards/Technology Training 71 © Nokia Siemens Networks
MC와 CA의 차이점 •
MC (Multi Carrier) • • • •
•
예: SKT가 현재 850MHz 2x10MHz와 1.8GHz의 2x10MHz에서 MC LTE를 운용 중 850MHz망만 운용하는 것에 비하여 시스템 용량은 2배 증가 한 단말기가 동시에 850MHz와 1.8GHz를 사용하지 않으므로, 단말 구현의 난이도는 높지 않음 한 단말기가 동시에 850MHz와 1.8GHz를 사용할 수는 없으므로, 사용자 PDR은 2배로 증가하지 않음 여전히 DL 75Mbps
CA (Carrier Aggregation) • • • •
한 단말기가 동시에 N개의 주파수를 동시에 사용할 수 있음. 이에 따라 위의 SKT의 예에서는 사용자 PDR이 2배로 증가 가능 최대 DL 150Mbps 실제 시스템 용량은 MC에 비하여 크게 증가하지 않음 단말기 구현의 난이도가 높음 • Intra-band contiguous CA (하) • Intra-band non-contiguous CA • Inter-band (non-contiguous) CA (상)
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Some options of CA terminal implementation
TTA LTE Standards/Technology Training 73 © Nokia Siemens Networks
Carrier Aggregation bands Release independent Carrier Aggregation bands in 3GPP Rel-11 Inter-band CA: CA Band
Carrier aggregation bands in 3GPP Rel-10 (Source: TS36.104, version 10.9.0) Intra-band CA:
CA Band CA_1 CA_40
Inter-band CA:
CA Band CA_1-5
E-UTRA operating band 1 40 E-UTRA operating bands 1 5
CA_1-19 CA_3-7 CA_4-13 CA_4-17 CA_7-20 CA_5-12 CA_4-12 CA_2-17 CA_4-5 CA_5-17 CA_3-5 CA_4-7 CA_3-20 CA_8-20 CA_1-18 CA_1-21 CA_11-18 CA_3-8
E-UTRA operating band 1 + 19 3+7 4 + 13 4 + 17 7 + 20 5 + 12 4 + 12 2 + 17 4+5 5 + 17 3+5 4+7 3 + 20 8 + 20 1+18 1+21 11+18 3+8
Requested by NTT DOCOMO TeliaSonera Verizon Wireless AT&T Orange et al US Cellular Cox Communication AT&T AT&T AT&T SK Telecom Rogers Wireless Vodafone Vodafone KDDI NTT DOCOMO KDDI KT
Intra-band CA:
CA Band
TTA LTE Standards/Technology Training 74 © Nokia Siemens Networks
CA_41 CA_38 CA_7
E-UTRA operating band 41 38 7
Requested by Clearwire, CMCC,… CMCC CUC, CT, Telenor et al
User plane structure – Downlink • Compared to the Layer 2 structure of LTE Rel-8, the multi-carrier nature of the physical layer is only exposed to the MAC layer for which one HARQ entity is required per CC. • The Layer 2 structure for the downlink is depicted here: There is one PDCP and RLC per Radio Bearer. Not visible from RLC on how many CCs the PHY layer transmission is conducted. RLC supports data rates up to 1Gbps.
Radio Bearers ROHC
...
ROHC
Security
RLC
ROHC
...
ROHC
...
PDCP ...
Security
Segm. Segm. ... ARQ etc ARQ etc
Security ... Security
...
Segm.
Segm. Segm. ... ARQ etc ARQ etc
Segm.
CCCH BCCH PCCH
Dynamic Layer 2 packet scheduling across multiple CCs supported, (provided that UE is configured to transmit/receive those multiple CCs). Independent HARQ per CC. Thus, HARQ retransmissions shall be transmitted on the same CC as the corresponding original transmission.
TTA LTE Standards/Technology Training 75 © Nokia Siemens Networks
MCCH
Logical Channels Unicast Scheduling / Priority Handling
Multiplexing UE1
...
MBMS Scheduling
Multiplexing
Multiplexing UEn
MAC
HARQ
...
HARQ
HARQ
...
HARQ
Transport Channels DL-SCH on CC1
DL-SCH on CCx
DL-SCH on CC1
DL-SCH on CCy
BCH
PCH
Separate transport channels per CC: •One transport block per TTI (when no spatial mux) •Separate HARQ entities and retransmissions
MCH
MTCH
User plane structure – Uplink Radio Bearers ROHC
ROHC
Security
Security
PDCP
RLC
Segm. ARQ etc
...
decides: • •
Segm. ARQ etc Logical Channels
Scheduling / Priority Handling
MAC
Multiplexing
HARQ
...
HARQ Transport Channels
CC1
...
CCx
TTA LTE Standards/Technology Training 76 © Nokia Siemens Networks
Same general principle as for downlink: • Independent synchronous HARQ per CC. • If UE is scheduled on multiple CCs, the UE Which order it utilizes the grants How to multiplex data from different radio bearers on CCs (based on logical channel prioritization rules).
• Separate transport channels per CC.
CC/Cell management:
PCell/SCell concept
• CA is configured for a UE • RRC Connected state only • Single RRC Connection (in standards perspective) • No effects to the Idle mode
Primary Cell (PCell): •Provides Security inputs •Provides NAS mobility functions •Used for PUCCH transmission •Used for RRC connection re-establishment •Can be changed only by Handover •Cannot be deactivated •Cannot be cross scheduled •Have always Uplink and Downlink resources Carrier frequency (FDD) or UL/DL subframes (TDD) •Used for Radio Link Monitoring •In summary: UE operates in PCell in similar manner as in Rel8/9 serving cell TTA LTE Standards/Technology Training 77 © Nokia Siemens Networks
Secondary Cell (SCell): •SCells are configured based on UE capability •Can have DL only resource or DL and UL resource •Are Rel-8 backward compatible cells •Are configured to be used by the UE by dedicated signaling (RRC Reconfiguration) •Providing additional resources for UEs connection •Can be deactivated; Both UL and DL is deactivated simultaneously •Can be cross scheduled from PCell or from other SCells but always from single location •UE acquires system information of SCell by dedicated signaling (RRC Reconfiguration)
Cell Configuration • Pcell – Existing PCell is implicitly indicated – Cell index for PCell is implicitly “0” – PCell is changed only with handover (i.e. RACH and security change) • Scell – Delta configuration to the existing SCell applied – Existing SCell is explicitly indicated by frequency or cell index – Full configuration is used for SCell addition – SCell can be added / removed / reconfigured for a UE at any time the eNB wants to do so
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Normal or cross-carrier scheduling
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CA approach to interference avoidance in HetNet
TTA LTE Standards/Technology Training 80 © Nokia Siemens Networks
SON
TTA LTE Standards/Technology Training 81 © Nokia Siemens Networks
Why SON?
• 기지국 수의 증가 설치 및 운용 비용 증가 • Performance optimization 빈번한 re-configuration 필요 TTA LTE Standards/Technology Training 82 © Nokia Siemens Networks
Nokia Siemens Networks’ SON Suite is built on our detailed understanding of how networks operate Nokia Siemens Networks SON Suite Self configuration
Plug and Play Open northbound interfaces
Automated Neighbor Relations
Minimization of Drive Tests
Mobile Core
LTE SON SON
Power saving
Self optimization
Load balancing Interference optimization
Other vendor network
Mobility robustness
Self healing
Cell outage detection & compensation Self healing / alarm management
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2G/3G SON
LTE-Advanced Improvements
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Thank you ! www.nokiasiemensnetworks.com Nokia Siemens Networks 20F, Meritz Tower, 825-2 Yeoksam-Dong, Kangnam-Gu Seoul 135-080, Korea
Bong Youl (Brian) Cho Lead Product Manager – Korea, Ph. D LTE Business Line, MBB
[email protected] Mobile 010-4309-4129 TTA LTE Standards/Technology Training 85 © Nokia Siemens Networks
